cleanup for r1812476: avoid NPEs from string.isEmpty()

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1812516 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/poifs/crypt/CryptoFunctions.java

@@ -374,6 +374,10 @@ public class CryptoFunctions {
      * @return the verifier (actually a short value)
      */
     public static int createXorVerifier1(String password) {
+        if (password == null) {
+            throw new IllegalArgumentException("Password cannot be null");
+        }
+
         byte[] arrByteChars = toAnsiPassword(password);
         
         // SET Verifier TO 0x0000
@@ -412,6 +416,10 @@ public class CryptoFunctions {
      * @see <a href="http://www.aspose.com/blogs/aspose-blogs/vladimir-averkin/archive/2007/08/20/funny-how-the-new-powerful-cryptography-implemented-in-word-2007-turns-it-into-a-perfect-tool-for-document-password-removal.html">Funny: How the new powerful cryptography implemented in Word 2007 turns it into a perfect tool for document password removal.</a>
      */
     public static int createXorVerifier2(String password) {
+        if (password == null) {
+            throw new IllegalArgumentException("Password cannot be null");
+        }
+
         //Array to hold Key Values
         byte[] generatedKey = new byte[4];
 

src/java/org/apache/poi/ss/formula/eval/StringEval.java

@@ -17,6 +17,8 @@
 
 package org.apache.poi.ss.formula.eval;
 
+//import org.checkerframework.checker.nullness.qual.NonNull;
+
 import org.apache.poi.ss.formula.ptg.Ptg;
 import org.apache.poi.ss.formula.ptg.StringPtg;
 
@@ -27,6 +29,7 @@ public final class StringEval implements StringValueEval {
 
 	public static final StringEval EMPTY_INSTANCE = new StringEval("");
 
+	//@NotNull
 	private final String _value;
 
 	public StringEval(Ptg ptg) {

src/java/org/apache/poi/ss/usermodel/FractionFormat.java

@@ -150,7 +150,7 @@ public class FractionFormat extends Format {
         }
         
         //if whole part has to go into the numerator
-        if (wholePartFormatString.isEmpty()){
+        if (wholePartFormatString == null || wholePartFormatString.isEmpty()){
             int trueNum = (fract.getDenominator()*(int)wholePart)+fract.getNumerator();
             sb.append(trueNum).append("/").append(fract.getDenominator());
             return sb.toString();

src/ooxml/java/org/apache/poi/poifs/crypt/dsig/services/RelationshipTransformService.java

@@ -205,7 +205,7 @@ public class RelationshipTransformService extends TransformService {
                 String id = el.getAttribute("Id");
                 if (sourceIds.contains(id)) {
                     String targetMode = el.getAttribute("TargetMode");
-                    if (targetMode.isEmpty()) {
+                    if (targetMode == null || targetMode.isEmpty()) {
                         el.setAttribute("TargetMode", "Internal");
                     }
                     rsList.put(id, el);

src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextRun.java

@@ -845,7 +845,7 @@ public class XSLFTextRun implements TextRun {
                 }
                 // SYMBOL is missing
                 
-                if (font == null || !font.isSetTypeface() || font.getTypeface().isEmpty()) {
+                if (font == null || !font.isSetTypeface() || "".equals(font.getTypeface())) {
                     font = coll.getLatin();
                 }
             }